Framework for EVPN Designated Forwarder Election Extensibility
draft-ietf-bess-evpn-df-election-framework-01
BESS Workgroup J. Rabadan, Ed.
Internet Draft Nokia
S. Mohanty, Ed.
Intended status: Standards Track A. Sajassi
Cisco
J. Drake
Juniper
K. Nagaraj
S. Sathappan
Nokia
Expires: October 14, 2018 April 12, 2018
Framework for EVPN Designated Forwarder Election Extensibility
draft-ietf-bess-evpn-df-election-framework-01
Abstract
The Designated Forwarder (DF) in EVPN networks is the PE responsible
for sending broadcast, unknown unicast and multicast (BUM) traffic to
a multi-homed CE, on a given VLAN on a particular Ethernet Segment
(ES). The DF is selected out of a list of candidate PEs that
advertise the same Ethernet Segment Identifier (ESI) to the EVPN
network. By default, EVPN uses a DF Election algorithm referred to as
"Service Carving" and it is based on a modulus function (V mod N)
that takes the number of PEs in the ES (N) and the VLAN value (V) as
input. This default DF Election algorithm has some inefficiencies
that this document addresses by defining a new DF Election algorithm
and a capability to influence the DF Election result for a VLAN,
depending on the state of the associated Attachment Circuit (AC). In
addition, this document creates a registry with IANA, for future DF
Election Algorithms and Capabilities. It also presents a formal
definition and clarification of the DF Election Finite State Machine.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
Rabadan, Mohanty et al. Expires October 14, 2018 [Page 1]
Internet-Draft DF Election Framework for EVPN April 12, 2018
other groups may also distribute working documents as Internet-
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This Internet-Draft will expire on October 14, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Internet-Draft DF Election Framework for EVPN April 12, 2018
Table of Contents
1. Conventions and Terminology . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Default Designated Forwarder (DF) Election in EVPN . . . . 4
2.2. Problem Statement . . . . . . . . . . . . . . . . . . . . . 5
2.2.1. Unfair Load-Balancing and Service Disruption . . . . . 6
2.2.2. Traffic Black-Holing on Individual AC Failures . . . . 7
2.3. The Need for Extending the Default DF Election in EVPN . . 9
3. Designated Forwarder Election Protocol and BGP Extensions . . . 10
3.1 The DF Election Finite State Machine (FSM) . . . . . . . . . 10
3.2 The DF Election Extended Community . . . . . . . . . . . . . 13
3.3 Auto-Derivation of ES-Import Route Target . . . . . . . . . 15
4. The Highest Random Weight DF Election Type . . . . . . . . . . 15
4.1. HRW and Consistent Hashing . . . . . . . . . . . . . . . . 16
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